Printing head nozzle evaluation

Abstract

A method for evaluating performance of a plurality of nozzles of a printing head includes repeatedly operating each of the nozzles to print test marks on a surface of a substrate, each of the test marks printed by that nozzle being printed at a different time. At least once during the repeated operation of each of the nozzles, at least some of the test marks are erased from the surface. The test marks that were printed by that nozzle are inspected for a feature that is indicative of the performance of that nozzle.

What is claimed is: 
     
         1 . A system for evaluating performance of a plurality of nozzles of a printing head, the system comprising:
 an imaging device for acquiring images of test marks that were printed on a substrate surface by each of the plurality of nozzles;   a processor configured to:
 inspect the test marks to determine whether test marks printed by a particular nozzle of the plurality nozzles are identical in appearance; 
 identify a set of test marks from the test marks that were printed by a particular nozzle and that are not identical in appearance; 
 identify the nozzle that printed the identified set of test marks; 
 exclude the identified nozzle from the plurality of nozzles to generate a set of conforming nozzles; and 
 select the set of conforming nozzles to print a multi-layered line of metallic material; and 
   
       an eraser device for erasing the test marks from the substrate surface. 
     
     
         2 . The system of  claim 1 , wherein the eraser device comprises a wiper for erasing the test marks when the wiper is rubbed against the substrate surface. 
     
     
         3 . The system of  claim 2 , wherein the eraser device comprises a dispenser for dispensing a wiper foil such that the wiper foil is inserted between the wiper and the substrate surface when the wiper is rubbed against the substrate surface. 
     
     
         4 . The system of  claim 3 , wherein the wiper foil comprises paper. 
     
     
         5 . The system of  claim 1 , wherein the wiper comprises a resilient material at least partially surrounded by an abrasive material. 
     
     
         6 . The system of  claim 5 , wherein the abrasive material comprises plastic fibers. 
     
     
         7 . The system of  claim 1 , further comprising: a conveying device for conveying the substrate surface to one or more of the printing head, the imaging device, and the eraser device.